1. Field of the Invention
This invention relates to a battery pack and more particularly it relates to improvements in a construction for attaching contact terminal means acting as charging or discharging terminals in a battery pack housing a plurality of interconnected unitary cells.
2. Description of the Prior Art
Battery packs to which the invention is directed are used as power source devices for such portable units as video cameras, televisions, radios, tape recorders, and toys. Battery packs usually contain a plurality of interconnected unitary cells for source voltages specified for such portable units. To facilitate the handling of such a plurality of unitary cells, these unitary cells are integrally housed in an outer case, which has attached thereto terminals for electrical connection to such discharging devices as the aforesaid portable units. In most cases, the battery device is so designed that when it is simply inserted into the battery receiving section provided in the discharging device, desired electrical connection is established between it and the discharging device and the positioning of the battery pack itself is attained. That is, it is so arranged that when the battery back is positioned in the battery receiving section, the terminals of the battery pack come in contact with the terminals of the connector section of the discharging device.
Further, to enable such battery pack to be used repeatedly, there is a case where the unitary cells housed in the case are secondary cells, such as rechargeable nickel-cadmium cells or lead acid cells. In this case, the combination of the terminals for discharging is made different from that of the terminals for charging in order to avoid making mistakes in electrical connection. Usually, in this case, there are three terminals, of which the first and second are used for discharging and the first and third for charging.
Battery packs which are of interest to this invention are disclosed in U.S. Pat. No. 4,123,598 granted to Hammel, and pending U.S. patent application Ser. No. 317,073 filed under the name of Hashimoto and assigned to the same assignee as in this application. The terminals provided in these prior art battery packs are exposed on the outer surface of the case. The arrangement wherein the terminals are exposed on the outer surface of the case is advantageous in that it facilitates electrical connection to a discharging or charging device, but on the other hand it encounters problems that the terminals are liable to suffer external damage and that shorts are liable to be caused as when some metal object accidentally comes in contact with the terminals.